The motorized skates known to the art are largely operated manually by means of a throttle, joystick, foot switch or other manual controls. U.S. Pat. Publ. No. 2003/0141124 to Mullet, U.S. Pat. No. 7,204,330 to Lauren and U.S. Pat. No. 5,829,543 to Diaz and many others disclose a motor mechanically connected to a wheel of the skate by gears, belts, cables or other indirect mechanical couplings, where the motor is controlled by the rider by means of a hand throttle or other manual speed control means. The skating devices known to the art, both without motors or with motors with manual speed control, have the disadvantage of requiring considerable skill and practice to utilize effectively and are not stable and controllable enough to be widely used with safety in a environment where significant other foot or vehicle traffic is present.
U.S. Pat. No. 6,059,062 to Staelin and U.S. Pat. No. 7,481,291 to Nishikawa teach a skate with motors and a means to modify the operation in response to weight transfer. Directly controlling the motor on each skate by weight transfer commonly causes motor action in response to normal skating or stepping actions where weight shifts forward and back on each foot. So when this approach to motor control is used, the skates often work against each other or work inappropriately if the rider does not keep their feet close together or if the rider attempts to step or skate.
U.S. Pat. Publ. No. 2006/0170174 to Hiramatsu and U.S. Pat. Publ. No. 2006/0213711 to Hara and U.S. Pat. No. 6,050,357 to Staelin et al. and U.S. Pat. No. 7,138,774 to Negoro et al. and U.S. Pat. No. 5,487,441 to Endo et al and other similar references all disclose skateboards with load sensors. These methods allow a rider to control a skateboard by leaning, or by shifting weight forward or backwards. However, these techniques are not suitable for use in skates for the same reasons as described above.
A further disadvantage of motorized skates known to the art is the presence of gears, cogs, belts, chains or other indirect torque transfer methods that introduce friction and sufficient energy loss such that the wheels to which the motors are coupled are not capable of freewheeling in a practical manner. This means that skating without assistance from the motor is not practically possible due to the drag effect from the motor. U.S. Pat. No. 6,428,050 to Brandley discloses a skate with a motor consisting of a rotor that is also the wheel of the skate and a stator that is located outside. However, the small amount of magnetic coupling provided between rotor and stator will severely limit the torque possible from such a motor.